ATP Production AP Biology Overview Life Is Work

ATP Production AP Biology

Overview: Life Is Work p p p Living cells require energy from outside sources Some animals, such as the giant panda, obtain energy by eating plants, and some animals feed on other organisms that eat plants Energy flows into an ecosystem as sunlight and leaves as heat Photosynthesis generates O 2 and organic molecules, which are used in cellular respiration Cells use chemical energy stored in organic molecules to regenerate ATP, which powers work

Adenosine Tri-Phosphate (ATP) ATP is the energy unit of the cell. p ATP is composed of an Adeno. Group, a sugar group and three phosphates. p ATP is easily recycled. p The cell converts Adenosine Di-Phosphate (ADP) into ATP by the addition of a phosphate. p

An Overview of how ATP is Produced

Fig. 9 -2 Light energy ECOSYSTEM Photosynthesis in chloroplasts CO 2 + H 2 O Organic +O molecules 2 Cellular respiration in mitochondria ATP powers most cellular work Heat energy

Redox Reactions: Oxidation and Reduction The transfer of electrons during chemical reactions releases energy stored in organic molecules p This released energy is ultimately used to synthesize ATP p

The Principle of Redox Chemical reactions that transfer electrons between reactants are called oxidationreduction reactions, or redox reactions • In oxidation, a substance loses electrons, or is oxidized p In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced) p

ATP powers cellular work by coupling exergonic reactions to endergonic reactions p A cell does three main kinds of work: n n n p p Chemical Transport Mechanical To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one Most energy coupling in cells is mediated by ATP

ATP (adenosine triphosphate) is the cell’s energy shuttle p ATP is composed of: p n n n ribose (a sugar) adenine (a nitrogenous base) Three phosphate groups

Fig. 8 -8 Adenine Phosphate groups Ribose

The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis p Energy is released from ATP when the terminal phosphate bond is broken p This Third Phosphate bond contains LOTS of Energy p This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves p

Fig. 8 -9 P P P Adenosine triphosphate (ATP) H 2 O Pi + Inorganic phosphate P P + Adenosine diphosphate (ADP) Energy

How ATP Performs Work p The three types of cellular work are: n n n mechanical transport chemical Each is powered by the hydrolysis of ATP p In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction p

Fig. 8 -11 Membrane protein P Solute Pi Solute transported (a) Transport work: ATP phosphorylates transport proteins ADP + ATP Vesicle Cytoskeletal track ATP Motor protein Protein moved (b) Mechanical work: ATP binds noncovalently to motor proteins, then is hydrolyzed Pi

Phosphorylation ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant p The recipient molecule is now phosphorylated p

Phosphorylation The process of Phosphorylation converts a relatively low energy compound (ADP) into a higher energy compound (ATP) p ADP (Adenosine Di-Phosphate)- Contains an Adenosine, a ribose group, and two Phosphate groups. p

Fig. 8 -12 ATP + H 2 O Energy from catabolism (exergonic, energy-releasing processes) ADP + P i Energy for cellular work (endergonic, energy-consuming processes)

The ATP Cycle ATP can be produced from existing ADP molecules p A phosphate is added to ADP at the mitochondria. p Requires ATP synthase - A protein complex in the mitochondria that acts a molecular mill and converts ADP into ATP. p

Fig. 9 -UN 7 INTERMEMBRANE SPACE H+ ATP synthase ADP + P i MITOCHONDRIAL MATRIX ATP H+

The Regeneration of ATP p p ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP). Requires ATP synthase and H ions (from water. ) • • The energy to phosphorylate ADP comes from catabolic reactions in the cell. The chemical potential energy temporarily stored in ATP can then be used to drive most cellular work.